Pointer and pen carrying mechanism for indicators, controllers and recorders



v E. D. HAIGLER POINTER AND PEN CARRYING MECHANISM FOR INDICATORS, CONTROLLERS AND RECORDERS Nov. 3, 1959 4 Sheets-Sheet 1 Filed Sept. 4, 1953 INVENTOR. EDMUND D. HA/GLER BY sf A TTORNE Y Nov. 3, 1959 E. D. HAlGLER 2,911,278

- POINTER AND PEN CARRYING MECHANISM FOR INDICATORS, CONTROLLERS AND RECORDERS Filed Sept. 4. 1953 4 Sheets-Sheet 2 IN VEN TOR.

EDMUND D. HA/GLER ATTORNEY Nov. 3, 1959 E. D. HAIGLER 2,911,278

\ POINTER AND PEN CARRYING MECHANISM FOR INDICATORS, CONTROLLERS AND RECORDERS Filed Sept. 4, 1953 4 Sheets-Sheet 3 I27 I25 Ill lll 12 6 926 Fig. [0.

INVENTOR EDMUND 0. HA/GLER ATTORNEY Nov. 3, 1959 E. D. HAIGLER 2,911,278

POINTER AND PEN CARRYING MECHANISM FOR INDICATORS, CONTROLLERS AND RECORDERS Filed Sept. 4, 1953 4 Sheets-Sheet 4 KM "1 I46 I J- /47 f 152 /40 lg I /39 I42 l4/8/42 FF'g. 6. Fig. 78. Fig. 7A.

INVENTOR EDMUND 0. HA IGLER ORNEY United States Patent POINTER AND PEN CARRYING lVIECI-lANISM FOR 7 INDICATORS, CONTROLLERS AND RECORDERS Edmund D. Haigler, Hatboro, Pa., assignor to Fischer & Porter Company, Hatboro, Pa., a corporation of Pennsylvania This invention relates to 'pen movement indicating and recording instruments such as those generally used in industrialprocesses for measuring and/or controlling pressure, temperature, humidity, flow, liquid-level, specific gravity, viscosity and other measurements.

Commonly, recorders using circular charts have one to four pens connected with as many measuring elements. Controllers may have one and sometimes two measuring elements conneced to one or two control systems, and it is the usual practice to provide one pointer for each controller-setting in addition to the pen-record of the measurement operating the controller. Because of rapid change and the development of processes using industrial instruments, it is desirable that an instrument be revised readily to meet changing requirements. This may involve changing measuring elements or adding pens or a controlsystem. At the same time it is important that the 'cost of the simpler instruments not be increased unduly in arriving at the desired flexibility.

In general there are two types of pen movements, coaxial systems in which the several pens (or pointers) operate on the same axis, and adjacent axis systems to which this invention particularly applies. Unfortunately, coaxial systems, while providing for arcing successive pens at a minimum time interval between each other on the chart, are inherently either inflexible or uneconomical. Conversion of a coaxial system, by manufacturer or user usually involves complete disassembly of the pen movement and reassembly, often with-largely difierent parts.

In the adjacent-axis system, where successive pen axes are side by side rather than coaxial, it is essential that p the interval between axes be small in order that successive pens may follow closely the same time are on the chart with ,a minimum time-interval between them. While the adjacent spindles in the pen movement may be identical, unlike the coaxial movement design, the basic spindle has to be equipped with a pen or pen-supporting bracket, with a lever to receive motion from a measuring element, and often with additional levers to transmit motion to a controller, integrator, alarm switch or other devices. To secure strength in the limited space between spindles, it has been customary to weld or solder such levers in place.

Thus flexibility, which might seem inherent in the adjacent axes movement, is not realized because of the very large assortment of spindle assemblies required with v difierent lever heights and angles for the many combinations'of numbers of pens, locations of elements and choice of control functions which may be encountered. The chief advantage of the usual adjacent axis pen moveinent is that the pivot plates and supporting posts need not be changed for one, two, or three spindles. Four or more" spindles cannot be'used with such designs because of the problems of spacing and 'flexibility, unless extensive modifications are made.

p object of this invention is to provide a pen move "ice 7 Patented Nov. 3, 1959 2 ment of the adjacent axes type, with effective flexibility for manufacture and use.

It is also an object of this invention to provide a pen movement having convenient continuous lateral and angular adjustments and clamping of levers on I the spindles.

It is another object to provide a pen movement wherein measuring spindles or control setting spindles may be added without dismantling and possibly upsetting the adjustment of the spindles already present.

It is a still further object of this invention to provide apen movement having a minimum number of parts that will make a large repertoire of dilferent assemblies.

It is also an object of this invention to provide a pen movement in such form that the manufacturing and tool ing is simple and lends itself to multiple use.

Another object of this invention is the provision of an adjacent axis pen movement having'as many as four spindles.

For the purpose of illustrating the invention, there are shown in the accompanying drawings forms thereof which are at present preferred, although it is to be'understood that the various instrumentalities of which the invention consists can be variously arranged and organized and that the invention is not limited to the precise arrangements and organizations of the instrumentalities as herein shown and described.

Figure 1 represents perspective view of a dual con troller pen movement, with two recording pens and two setting pointers. I

Figure 2 represents a front elevation of the pen movement of Figure l.

. Figure 3 represents a plan view of the pen movement of Figure 1.

Figure 4 represents a detail of a spindle.

Figure 5 represents a front elevation of the pen lever assembly.

Figure 6 represents a side elevation of the pen lever assembly.

Figure 7 represents a front elevation of the pen arm.

Figure 7A represents an enlarged view of the pen arm.

Figure 78 represents a section on line BB of Figure 7.

Figure 8 represents a side elevation of the pen arm.

Figure 9 represents a front elevation of the end of the pointer formed from the pen blank and interchangeable therewith. 1

Figure 10 representsan enlarged view of the pivot or trunnion end of a spindle.

1 Figure 11 represents an enlarged rear view of the assembled pen micrometer and spring adjustably connecting the pen to the pen lever.

Figure 12 represents an enlarged view of the clamping of the pen lever assembly on the spindle.

Figure 13 represents an enlarged view of the rotation of a pen lever assembly to clamp on another face of the spindle than that shown in Figure 12.

Figure 14 represents a plan view of a straight lever.

Figure 15 represents an enlarged view of the adjusting sector for an adjustable angle input.

Figure 16 represents a plan view of a lever component. Figure 17 represents a plan view of another embodiment of a lever component. T V Figure 18 represents a plan view of another embodiment of a lever component.

Figure 19 represents a plan View of an adjustable angle input lever.

The pen movement has a frame or cage 101 composed of a back bearing plate 102 clamped between the sub-base (or the back of the instrument case) 103 and the posts 104 by back screws 105 passing through clearance holes 106 in opposite ends of bearing plate 102 and H s :,.'..--.;J

, threading at 107 into posts 104.

On the opposite end of posts 104 is mounted intermediate plate 108, tubular spacers 109, and front bearing plate 102', held in place by front screws 110 extending through clearance holes 106' through front bearing plate 102' and through spacers 108 into threaded holes 107" in the front ends of posts 104.

yAS shown in Figure 3, clearance holes 106 in bearing plates 102 in intermediate plate 108 are considerably larger than the shanks of screws 105 and 110 leaving clearance for hubs 111 on each end of posts 104 and spacers 109. These hubs are closely sized to holes 106 and extend less than half the plate thickness. Thus when the screws 105 and 110 are tightened, plates 102 and 108 are clamped in accurate alignment with substantial lateral and vertical stiffness by reason of the bearing and clamping radii being well out on the relatively large diameter posts 104 and spacers 109.

The front and back bearing plates 102, 102 are preferably made of a bearing material such as nickel-silver, each containing four pivot holes, 112A to 112D, closely and equally spaced along that diagonal line through the approximate center of the plate which when projected intersects the pen arc of the chart at its midpoint. Two pivot holes 112D and 112C are above and two holes 112B and 112A below the center, the charts being laid out so the time arcs swing from midway between pivot holes 112B and 112C, and are nearly correct for pen arm lengths corresponding to holes 11213 and 112C in bearing plate 102. The bearing plate 102 also contains two holes 113 to serve as front bearings for right and left controller setting spindles 114.

Intermediate plate 108 has a number of functions. It contains two holes 115, in alignment with holes 113 in front bearing plate 102', to serve as rear bearings for controller setting spindles 114. Made of stainless steel or other sturdy metal, intermediate plate 108 also serves as a stiffener to the entire assembly. it carries two ears 116 with threaded holes 117 to support an upper chart plate 118 screwed to it, covering and protecting the mechanism behind it in the upper part of the case. ear 119 bent forward at right angles to the plate 108 carries a pen lifter 120 which pivots in a hole in the ear and is frictionally held by flat U-spring 121 either in an operating position against the chart plate but slightly raised above the rotating chart by a lug 122 under the pen lifter 120 and resting outside the chart, or in the chart change or lifted position lifting the pens at 123 off the chart. A clearance slot 124 is provided for the spindles, as seen in Figure 1 In the simplest indicators or transmitters, which require no setting-spindle assemblies 114 nor supporting ears for chart plate 118, nor pen lifter 120, the intermediate plate 108 may be omitted and posts 104 used without spacers 109 the pointers to track perfectly on the scale arc is barely noticeable, so itsuifices to use a layout correct for recorders even though somewhat incorrect for indicators,

avoiding the inconvenience of different bearing plates for indicators. J

Pen spindles 125 are preferably fabricated of. strong corrosive-free metal, in particular hard drawn stainless steel rod, preferably hexagonal in cross section although other polygonal forms may be used. Pivots or trunnions 126 at each end of the spindle are barrel-shaped to permit operation at very close clearances. in the pivot holes 112 without the necessity for perfect alignment of front. and back plates as would. be. required with equally close-fitting cylindrical pivots.

Another Circular shoulders 127 adjacent to pivots 126 accept any slight end thrust without any gouging of plates 1102 and 102' by corners of the hexagonal shaft.

In a single-pen indicator or recorder, one spindle is assembled in hole 112B with a pen lever assembly 130 between intermediate plate 108 and front plate 102 and an input lever between intermediate plate 108 and rear plate 102.

Pen lever assembly 130, shown in more detail in Figure 5, consists of a stainless steel punching 131,, genere ally arcuate in shape to permit swinging around lower spindles when used on an upper spindle. 'At the spindle end of pen lever 130 (see Figure 6) a right angle portion 132 and a leg 133 at a right angle to portion 132 form a U-shaped end 91, in the opposite legs of which specially shaped holes 134 are punched (see Figures 12 and 13). A threaded set screw hole 135 with set screw 136 is provided in the bottom of the U-shaped end 97'. At the other end of the arc is a penarm rivet 137, beyond which lever extension 138 has an car 138 containing threaded hole 140, turned back at a right angle to the side of this extension.

Pen arm 141 (Figures 7 and 8) and pointer 142 (Figures 9 and 10) are punched at their upper ends with holes 143 slightly smaller than the intermediate diameter 144 of pen arm rivet 137. II his rivet-fitting hole is slotted out at the upper end of the pen arm in a. wide wedgeshaped entrance slot 145 which will start over the rivet, and is slotted for a ways below the rivet-fitting hole in a narrow slot 145 to provide flexibility for snapping over the rivet and gripping it firmly. rivet 137 confines the pen arm end on intermediate diameter 144 between rivet head 147 and pen arm lever 130 into which rivet 137 is staked. An ear 148 turned up at right angles on the pen arm or pointed, a small. distance below rivet-fitting hole 143, contains clearance hole 149', which, when the pen arm is snapped on the pen lever, falls in alignment with threaded hole 140 on the pen lever 130.

A dimple 150 is raised near the lower end of pen aim 141 to engage a corresponding hole in the pen, thereby assuring that it will not separate from the arm or lose its correct radius as the result of vibration in service or in shipment. Intermediate portion 151 of the arm is formed into a shallow V 152 for stifiening, as shown in Figure 7B, since a long thin perfectlyfiat pen arm might be unduly flexible, it being desirable to make pen arms of thin material for lightness in order teat weight loading of measur ing elements may be kept low.

As shown in Figure 11, pen arm 140 or pointer 141 is adjustably attached to pen lever 130 by micrometer screw 153 engaging the ears 148 and 139 and holding. them against thereaction of the micrometer spring 154. \One end of spring 154 is reduced in diameter so that it is a very' tight fit on the threaded shank of adjustment screw 153, but is a free fit on the reduced diameter 155. under the head, thus permitting non-losable assembly of spring 154 and micrometer screw 153 on pen arm 141 or pointer 142. With the above described construction, the angular relationship between pen arm and pen lever can be precisely adjusted through slight turning of the knurled and slotted head of micrometer screw 153, while spring 154 takes up all shake in the threads, and serves as a friction lock thereon. Pen arm 141 may be readily removed from the pen lever 130 by simply unscrewing micrometer screw 153 from threaded hole 140 in pen lever 130, and then unsnapping the upper end of pen arm. 141 from. pen arm rivet 137. Point 155 on adjusting screw 153 facilitates reentry into hold 140'for reassembly of the largely con cealed adjustment.

The clamping of the penarm lever and other levers on hexagonal spindles is best explained by reference to Figure 12. It is to be noted that if the two spindle holes v 134 in the U-formed end 97 of lever were hexagonal, fitting the spindle, it would be possible to clamp the lever at a.

A head 147 on pen armdesired lateral position on the spindle by tightening set screw 136 in the threaded hole 135 against the spindle. This would force the spindle against the opposite side of the holes. However, it is found by actual trial of such construction that the holes must be an extraordinarily precise fit upon the spindle to avoid transverse working or rocking of the lever on the spindle, gradually loosening the set screw. It is also found with such construction that a secure grip is only-possible with a relatively large set screw which in turn requires a large U in the lever and a large stifi spindle, which are impractical for the present purposes.

-'In the pen movement embodiment of this invention no attempt is madeto have holes 134 fit spindle 125 except on two slanting sides 156 opposite set screw 136. Side 157 directly opposite the set screw is relieved so it never touches the spindle (see Figure 12). 'Thus it is possible with a small set screw and a relatively small light U-end 97 on the lever to secure a very strong secure wedging action whichprecludes any possibility of working and loosening the set screw. Of course, for utmost security, it is possible also to use a knurled end or other type of self-locking set screw, although this is usually not necessary. .The shape of hole134 or amount of clearance on its remaining sides 99 is .immateriahbut it is essential that there be such clearance, bothfor freedom in lateral adjustment when the set screw is loose, and to avoid interference with the wedging on engaging faces 156 when set screw 136 is tightened, particularly in case of slight variations in shape or dimensions ofthe mating parts.

Moreover, by enlarging hole 134 on the set screw side 158 and the adjacent sides 99 which are opposite wedging faces 156 spindle 125 can be cleared when it is rotated in the holes as indicated in Figure 13. c On loosening set screw 136 slightly, lever 130 may be slid along the shaft, and on loosening it considerably lever 130 may be rotated upon the shaft. Yet when the set screw 136 is lightly tightened, so lightly as not to stress the spindle 125 or pivots 12 6 unduly, the lever is very firmly locked to the spindle at the desired angle and lateral position.

,An input lever designated 1 60 is preferably located on the spindle between intermediate plate 108 and back bearing plate 102 and is preferably equipped with a U-end 97a, wedging holes 134a, and set screw 136:; each analogous to the component elements on U-shaped end 97 of lever 130. A series of link holes 161' provide link connections at various radii for lever 160. Additional levers may be used to connect the measurement received at the spindle to alarm, control, integrator or other accessory function units. When the U-ends of these levers are faced oppositely on the spindle, levers disposed at different angles on the spindle may abut, bringing the link holes 161 laterally within the thickness of the stamping if need be. a p

In many instances it is necessary that one or more levers on each spindle be precisely adjustable to angles intermediate between the 60 jumps provided in the spindle holes 134, for which service adjustable levers can be used.

A preferred embodiment of an adjustable lever consists of a sector 162, shown in Figure 15 with the above described U-end 97b, spindle holes 134, plus a straight lever 163 (Figure 16) or hooked lever 164 (Figure 17-) or micrometer lever 165 (Figure 18) assembled thereto. Each of these angularly adjustable levers 163, 164, or 165 contains at its inner end a circular hole 166, just clearing the cross-corners diameter of the hexagonal spindle 125, and a tapped hole 167 at the radius of the sector slot 168 so that a binding head screw 169 with washer 170 can clamp it to sector 162 forming a rigid lever assembly (see Figure 19). By loosening screw 169 slightly, adjustment can be made within the 70 slot 168 of the sector, whereas by loosening set screw 136 slightly, the entire lever assembly can be adjusted laterally on the spindle. Continuous radial as well as lateral and angular adjustment is provided with lever combination 162 and 165, as lever 6 165 does not have a series of line holes 161 in fixed loca tions, but bears slider 171 continuously adjustedby the micrometer screw 172. This screw 172 is carried in holes in ears 173 and 174 raised at right angles from the body of the lever, and is held in place by its head bearing on the outside face of the outer ear, and by snap ring 175 on the inside face of the inner ear. A friction and antibacklash spring operates between lever 165, screw 172 and slider 171. The lever itself is so offset that link holes 176 in slider 171 travel along a true radius 166-476 to avoid interdependence of angle adjustment and radius or ratio adjustment in calibration of the instrument.

In multipen recorders, the order of use of the spindle holes is 112B, 112C, 112A and 112D, thereby assuring that the more common one and two pen instruments have the most precise pen arcing.

. In occasional double-depth instruments, additional back posts 176 and bearing plate 102" may be provided in back of subbase 103, as shown by the dotted extension in Figure 3, using extra long spindles which pass through clearance holes in the sub-base, and in the back bearing plate 102. Standard and extra long spindles may be used in the same unit, some pivot holes 112 in plate 102 being enlarged to clearance size whilethe others remain at original size. Alternatively a double depth movement may include another bearing plate back of the sub-base for use with separate spindle assemblies.

In recording controllers it is customary to provide at least one setting pointer under the pen, reading against the chart graduations. In this pen movement one such setting pointer is shown in 112A for use with record pen pivoted at 112B and another at 112D is for use with record pen pivoted at 1120. This pointer assembly consists of spindle 125, pen lever assembly 130, pointer 142, and setting sector 180 mounted between intermediate plate 108 and front bearing plate 102', and an adjustable radius and angle lever such as a combination of sector 162 and lever assembled on the spindle between intermediate plate 108 and the back bearing plate ,100. Setting sector 189, shown in Figure 2, is afiixed to the spindle in the manner of sector 162 and contains a large sector opening 181 whose outer radius 182 is slightly longer than the distance between the lower pivot hole 112A and right setting spindle bearing hole 113. The angular extent of opening 181 is just greater than the angular travel of the pens or pointers on the chart or scales, in this case about 35" Inside this sector opening 181 is setting spindle assembly designated 114, which provides a friction drive and lock for sectorand its spindle 125A..

Setting spindle assembly 114 consists of knurled set 'itng knob 183 with front bearing extension 184 fitting hole 113 and ending in front friction cone 185. Then reduced diameter shaft 186 continues through rear frict1on cone 187 (made double-faced to avoid misassembly), through pressure spring 188, through setting spindle bearing 115 in intermediate plate 108, and is held in place by the snap ring 189. Relatively low tapers of 5 on front friction cone 185 and rear friction cone 137 result in engaging setting sector 180 in essentialy point contact along the are 182. Under the force of pressure spring 188, a

very high unit pressure is developed at the contact point, and sector 180 is slowly and smoothly driven as spindle 114 is rotated. Because the point of contact is close to the center of setting spindle 114 and at a much larger radius on the setting sector 180 there is a substantial reduction ratio, without the backlash usually found in gear setting mechanisms. At the same time an automatic friction lock for any existing setting results. Furthermore if a-careless operator attempts to force the setting beyond either limit of travel in a way which would damage a geared setting mechanism, this friction drive slips without damage the end of the sector opening 181 striking setting sector shaft 186 above or below as stops, opening 181 being large enough to permit angular travel 7 matching the instrument scale, in the embodiment shown about 35.

The left setting sector may duplicate right setting sec: tor 180.

In multiple pointer segmental scale indicators, where the scale midpoint is vertically below the pen movement, and in segmental scale indicating controllers, interferences may be encountered in certain assemblies either between the arc of pen lever 130 and other spindles, or between sector 162 and other spindles. This is overcome by another pen lever having a different length of are for these indicators or by equivalent changes in sector 162, or in the angles of the U-ends or spindle-encircling hole, as seems most convenient.

The present invention may be embodied in other specific forms without departing. from the spirit or essential attributes thereof, and it is therefore desired that the present embodiments be considered in all respects as illustrative and not restrictive, reference being had to the appointed claims rather than to the foregoing description to indicate the scope of the invention.

1 claim:

1. A pen movement for automatic recording instruments including rigidlyspaced parallel frame plates, a plurality of spaced spindles rotatably mounted on trunnions intermediate said plates, at least one of said spindles having a portion of regular polygon shape in cross section and carrying a pen lever extending radially from said portion, said pen lever being laterally adjustable in respect to its spindle, locking means on said pen lever for locking said pen lever at difierent angles in respect to said spindle, said locking means comprising a U,-shaped end portion on said pen lever, aligned openings in the U-lcgs adapted to receive the named portion of the spindle, the edges of each opening remote from the base of the U being constructed and arranged to provide close wedged engagement with a plurality of the surfaces of said polygonal-shaped portion, a set-screw positioned in the base of the U adapted to engage the spindle when said spindle is received in the leg openings, and a pen arm for carrying a pen adjustably mounted on said pen lever at a point remote from said locking means.

2. A pen movement for automatic recording instruments including rigidly-spaced parallel frame plates, a plurality of spaced spindles rotatably mounted on trunnions intermediate said plates, at least one of said spindles having a portion of regular polygon shape in cross section and carying a pen leverextending radially from said portion, said pen lever being laterally adjustable in respectto its spindle, locking means on said pen lever for locking said pen lever at ditlerent angles in respect to said spindle, said locking means comprising a U-shaped end portion on said pen leverjaligned openings in the U-legs adapted to receive the named portion of the spindle, the edges of each opening remote from the base of the U being constructed and arranged to provide close wedged engagement with a plurality of the surfaces of said polygonal-shaped portion, the clearance in each of said legopenings juxtaposed to the aforesaid edges being sulficient to permit rotation of the spindle therein, a setscrew positioned in the base of the U adapted to engage the spindle when said spindle is received in the leg openings, and a pen arm for carrying a pen adjustably mounted on said pen lever at a point remote from said locking means.

3. A pen movement for automatic recording instruments including spaced parallel frame plates, a plurality of spindles rotatably mounted on trunnions intermediate said plates and each having a portion of regular polygon shape in cross section, an arcuate-shaped lever carried by each of said spindles, the radius of the arc of said lever being such that when the spindle carrying said lever is rotated the end of the lever most remote from the point of attachmentto the spindle is swingable about any spindle intermediate the remote end of the lever and the point of attachment for at least a significant portion of the peripheral surface of said intermediate spindle, each of said levers being laterally adjustable in respect to its spindle, locking means on each lever for locking said lever at different angles in respect to said spindle, said locking means comprising a U-shaped end portion on said lever, aligned openings in the U-legs adapted to receive the named portion of the spindle, the edges of each opening remote from the base of the U being constructed and arranged to provide close wedged engagement with a plurality of the surfaces of said polygonal-shaped portion, and a set-screw positioned in the base of the U adapted to engage the spindle when said spindle is received in the leg openings, with a portion of said lever remote from said locking means adapted to receive an indicator arm or the like.

4. A pen movement for automatic recording instruments including rigidly-spaced parallel frame plates, a plurality of spaced spindles rotatably mounted on trunnions intermediate said plates, at least one of said spin dles. carrying a pen lever, said pen lever being laterally adjustable in respect to its spindle, locking means on said pen lever for locking said pen lever at difierent angles in respect to said spindle, a pen arm for carrying a pen adjustably mounted on said pen lever at a point remote from said locking means, an adjustableinput lever carried on said spindle, said input lever being radially and angularly adjustable in respect to said spindle and comprising a sector member locked to said spindle by adjustable locking means permitting said sector member'to be locked at diiferent lateral positions in respect to said spindle, said input lever being freely rotatable about said spindle but confined to a predetermined degree of angular rotation by adjustable locking engagement with said sector member. I

5. A spindle-and-lever including a spindle having a portion of polygonal shape in cross section, a lever, a U-shaped end portion on said lever, aligned openings in the U-legs of said lever constructed and arranged to receive the spindle with the edges of each opening remote from the base of the U providing close wedged engagement with a plurality of the surfaces of the polygonallyshaped portion, a set screw entering said openings from the base of the U and adapted to engage the spindle when the spindle is received in the leg openings and lockingly wedge the spindle against the straight edges of each open ing remote from the base of the U. 7

References Cited in the file of this patent UNITED STATES PATENTS sssfszs Rush Apr. 21, 1908 7 1,309,240 Chappius July 8, 1919 1,925,515 Beck Sept. 5, 1933 2,002,686 Belaef May 28, 1935 2,125,060 Barnes et al. July 26, 1938 2,207,134 Staples July 9, 1940 2,410,335 Burdick Oct. 29, 1946 2,436,971 Moore Mar. 2, 1948 2,455,326 Bowditch Nov. 30, 1948 2,529,907 Blakeslee et al. Nov. 14, 1950 

